Metal-cutting machine



1,623,449 April 5 1927' A. a. THOMPSON ET A'- METAL CUTTING MACHINE Filed Nov. 17 1924 5 Sheets-Sheet 2 l nvenTors. ArthurG-.Thompson Linus K.Sprogue WMWI'W Anya.

1 623,449 Apnl 5 1927' A. e. THOMPSON ET AL METAL CUTTING MACHINE Filed Nov. l7 1924 5 Sheets-Sheet 5 75 lnvenTors.

AfihurCiThom son Linus K.Sprugue by I, An ys.

April 5 1927. 1,623,449

A. G. THOMPSON ET AL METAL CUTTING MACHINE FiledNov. l7 1924 5 Sheets-Sheet 4 lnvenTons. Arthur G.Thomps0n Linus K.sprugue WWW? Anvs 1 623,449 5 1927' A. e. THOMPSON E AL METAL CUTTING MACHINE Filed Nov. 1'7 1924 5 Sheets-Sheet 5 Fig. 10.

, lnvenTons. Arthur G.Thompson .L'lhus Ksp'rugue by Ms: M-

- Patented ARTHUR emu: 'rnomrsompr NEw Yoax, N. 1,, AND LINUs x. sraleeua, og' HAVEN, GONNECTICUT, ASSIGNOBS .ro THE NRY e, rnomrsoN a soar com, or NEW HAVEN, CONNECTICUT, a coarona'rroN or coNNae'rrcu'r.

METAL-CUTTING MACHINE.

Application filed November 17, 1924. Serial No. 150,285.

This invention relates to improvements in metal cutting machines 1n wh1ch the cutting action is performed by a ,IECIRIO- eating saw blade andthe general ob ect thereof is to provide a machine of this type which will cut with relatively high speed, with accuracy and with uniformity of tlme for each similar cut, and in which the saw blade will have afar longer and more efl'ective life than heretofore.

The present invention utlhzes th broad rinciples made the sub'ect of the p tent of lhompsori and Smith, 0. 1,596,033, granted August 17, 1926, and is therefore subsidiary to the broad invention disclosed and claimed in the said patent.

The princi al object of the present invention is therefbre to provide a metal cutting machine employing a saw blade having a reciprocating movement with alternatm cutting and return or idle strokes, n whlc machine shall be embodied the required correlation of its elements with the stock belng cut.

The object of the invention is,therefore, to provide a metal cutting machine f the reciprocating saw blade type in which the saw blade has its edge provided with teeth and with gullets intermediate the successive teeth, each of sufiicient capacity to receive and hold all of the metal cut by the following tooth in making one cut across the maximum cutting field or the maximum width of the stock being cut, in which means are provided for reciprocating the saw blade to give alternating 1 out and return strokes, with the return stro e in each case above the path of the cutting stroke, in which means are provided which act during the cutting stroke of the 'saw blade continuously, positively and uniformly to feed the saw blade relatively'to the work support, and in which machine (1) the speed of the saw bladeduring the cutting stroke,

(2) the. relative feeding movement between the saw blade and the stock or work support, (3) the resistive properties of the stock being cut, (4) the maximum cutting field or the maximum width of the stock being cut and (5) the capacity of the gullets of the saw blade are so correlated that each tooth during its cutting operation on the stock will cut metal therefrom of a maxi- -ing movement between the saw blade and mum bulk not greater than the capacity of a gullet and chiefly in strip form.

I The object of the. invention is further to provide such a machine in which the speed of the reciprocation of the saw blade ma be adjusted and the rate of the relative fee the stock or work support may be adjusted so as readily to enab e the required correlation to be effected according to the resistive properties of the stock bein cut, the size or maximum cutting field o the stock and the gullet capacity .of the saw blade employed so as to secure the required results while keeping within the endurance capacity of the saw blade or, in other words, without breaking the teeth of the saw blade or the saw blade itself. J

The object of the invention is further to provide feeding mechanism for the saw blade, acting during the cutting stroke with a variable movement compensatory to the variable reciprocatory' movement of the saw so that the feeding movement shall be uni-. form. It is obvious that the cutting stroke of a reciprocating sawblade will usually havea variable speed owin to the mechanism usually and necessari y employed for effecting reciprocation and to the character of the movement itself, which requires that the blade shall come to a dead stop at each end of each stroke. What is required to secure the desired results is that the feeding movement of the saw blade with respect to the work shall be uniform per unit of cutting stroke of the blade; that is to say, the uniformity required is not of absolute feeding movement, but the feeding movement varies in correlation with and in substantially the same proportion as the variations in the s eed of the saw.

The results of the invention are believed to be secured by providing continuous, positive and uniform relative feeding movement between the saw blade and the work. When this is done, the" time required to saw a given piece of stock may be accurately determined and will be the same at all times for the same size and character of stock, regardless of the number of cuts, until the saw blade is worn out. But the advantages of the invention may be obtained without a strictly uniform feeding move ment if tin remaining features of the invention be present, an if the relative feeding movement is continuous and positive,

provided the feeding movement is of such a character as to prevent the saw blade from stroke acts continuously, positively and uniforml already having at any time a :greater than a predetermined depth of penetration into the stockr' The invention in 'its preferred form, therefore, embodies a positlve screw feeding mechanism which during the cutting (using the latter term in the sense defined), to effect the feeding movement. With this type of feed, the saw blade is not only fed continuously and positively by reason of the. downward'thrust of the screw, but it is also fed uniformly by reason of the upward thrust of the screw, which prevents the saw blade from penetrating the stock to an extent 'reater than the predetermined amount. ith the screw type of feed such'as herein illustrated, the feeding movement is therefore continuous, POSI- tive and uniform, but: substantial advantages of the invention may be secured with any continuous, positively acting feed mechanism provided that, when an occasional occurrence of a decrease in the resistive proporties of the stock takes place, the saw is prevented from penetrating the stock to an extent, greater than the predeterminedamount. v

The invention also has for its object the provision of various novel mechanisms for securing various features of the inventionboth broadly considered and in the preferred form herein disclosed.

These and, other objects. and features of the invention will be made clear in theelementsof the feeding mechanism.

Fig. 5 is a detail in horizontal cross section taken on the line 5 5 of Fig. 6.

Fig. 6 is aside elevation'partially in vertical cross section of the lower portion of the construction shown in Fig. 4.

Fig. 7 is a side elevation of thecam and connections by which the lifting and lowering movements at the beginning and end of themlieturn stroke of the saw blade are secur Fig. 8 is a detail looking toward the right rename of Fig. 7 and taken in 'cross sectionfon the line 8-8. 1

Fig. 9' is a detail in perspective. and par-.

tially broken away, of'the crank mechanism for reciprocating the saw frame. F g. 10 is a. detail in side elevation'of the cam and connections by which the feeding mechanism is actuated. q

F1g. 11 is a detail view of a preferred form of a portion of a saw blade particularly adapted for. use this invention.

The machine herein selected for an embodiment of the present invention is in many of its general features similar to an ordinary type of power operated hack saw machine, and-hence it is only necessary to illustrate and describe in detail those featuresof the machine which are particularly concerned with the present invention.

The machine as illustrated presents a .generally rectangular base or supporting bed 1, which may be mounted on legs, not.

shown, or in any other' suitable manner. This supporting bed is provided at the rear end with suitable brackets and uprights such as 2, in which arejournalled the main driving or operating elements of the. ma-

chme- The main shaft 3 has fixedly mounted thereon a clutch disk 4. A pulley5, herein shown as of the cone or ste mounted on the shaft 3. X clutch member 6 of the wedge type is mounted to slideon the shaft 3 between the outer face of the' pulley 5 and a transverse pin 7 passing through the shaft 3. This clutchmember 6 has a rigid arm 8 pivoted at 9 to -crank 'arm 10, projecting from a shaft 11, journalled in a boss 12 formed on the bed support 1, This shaft 11 extends upwardly to a convenient point and is provided with an operating crank arm 13 having a handle 14.

The operative, therefore, by turning the handle 14, readily clutches the pulle 5 to, or unclutches it from, the clutch dis 4 and consequently the main shaft 3. Suitable'means are or adjustin the spec of rotation of the shaft 3, an thus the speed of reciprocation of the saw. Any specific means may be employed for this purpose, as such means specifically considered is old and common type, is loosely grovided for varying Ill and forms no part of the present invention. 7

In Fig. 3 there is illustrated a simple form of change speed drive which will effect this purpose. The driving belt 15 extends from the cone or step pulley 5 over an oppositely disposed cone or step pulley 16, mounted upon a shaft 17 driven from any suitable source of power. Consequently by shifting the belt 15 the speed may be varied as desired. Three changes of speed-are. indicated and will usually be found suflicient, but any number may be provided. 7

A shaft 18 is mounted above and parallel pinion and gear are preferably enclosed by the casing 21. At the side of the machine opposlte the driving pulley, a'third and stub shaft 22 is mounted above and parallel with the cam shaft 18 and carries rigidly secured-thereto the crank disk 23.

The saw frame 24 is of the usual inverted U-shape and has mounted in the lower ends of its arms the saw blade 25. This sawframe is provided with an upwardly extending guide boss 26, which is fitted to and slides upon the horizontally extending portion 27 of a saw guide arm, an offset extension 28 of which is'pivoted to swing about the axis of the cam shaft 18. This saw guide arm is further steadied in its movement by a brace arm 29 secured thereto by the set screw 30, offset in a direction opposite to that of the extension 28 and also pivoted to swing about the axis of the cam shaft 18. A handle 31 projecting from the guide arm 27 enables the guide arm with the saw frame and saw to be raised and lowered manually.

'The weight of the guide arm. saw frame and saw is preferably counterbalanced. For that purpose a link 32 pivoted at 33 to the guide arm extends downwardly beneath the supporting bed and is pivoted at 34 to a lever 35 fulcrumed at 36 on a bracket 37 projecting downwardly from the supporting bed. A counterbalancing weight 38 is hung on the free end of the lever 35. j

Means are also provided to hold the guide arm, saw frame nd saw in elevated position to a'low of the insertion and remova the stock. For this purpose a latch, shown in the form of a lever 39, is fulcrumed at 40 on the guide arm. Its upper arm has connected thereto a rod 41 sliding at its opposite end in an apertured boss'42 and 'provided with a handle .43 conveniently located adjacent the handle 31. The lower end of this latch lever 39 is notched at 44 and projects down through an opening in the supporting bed. .This latch preferably hangs 'out of pumb' so that when the guide arm is elevated, itwill swing to the left and the notch 44 will catch on the top of the bed and-hold the guide arm elevated. If necessary, the-operator may swing the latch into this position by pulling on the handle 43.

Upon pushing on the handle 43 the latch is released and the guide arm may then be lowered to cutting position.

The stock to be cut, an example of which is shown in the round bar 45, is rigidly held on the supporting bed 1 in cutting. position by means of a suitable work support.

A convenient form of work support is il-.

lof

lustratedhavingone fixed and one adjustable vise aw and having means by which it may be adjusted to bring the axis of the work at any required angle with respect to the ath of the saw blade. As illustrated, a wor supportlng bed plate 46 rests upon the supporting bed 1 and is pivoted at 47 thereto. A locklng bolt 48 projects down from the plate 46 through an arc-shaped slot 49 in the supporting bed, having its center of curvature at the pivot 47 Thus the work supportlng plate 46 may be adjusted at any desired angle with respect to the path of the saw. The work supporting plate carries, preferably formed integrally therewith, a fixed vise jaw 50. A movable vise jaw 51, having a base plate 52, is mounted to slide on the work plate 46 toward and from the fixed vise jaw. This base plate 52 is provided Will a locking bolt 53 extending down through a slot 54 in a longitudinally adjustable plate 55 mounted underneath and upon the work plate 46. An adjusting screw 56 1s swlvelled at 57 in the' adjusting plate 55 and threaded through the end of the work supporting bed plate 46. The projecting end of this screw to an operating handle 58. The locking bolt 58 provides a means for adjusting the movable vise jaw 51 approximately to its desired clamping position, while the fadjusting screw 56 provides a means by which the movable vise jaw may be then moved to clamp and unclamp the work.

The saw blade 25, as already pointed out, must have gullets of sufficient capacity to receive the entire amount of material cut by the respective teeth during their passage through the maximum cutting field. In order, therefore, to effect the required correlation of" this invention and enable the work to be performed-rapidly and economically, a saw blade is provided having very large and coarse teeth with corresponding large gulets. In practice the saw is provided with from four to seven teeth to the inch. These teeth 59 are preferably relieved at the front face. as indicated, by the angle between the vertical line 60 and the line 61 indicating the angle ofthe front face of the teeth. see Fig. 11. Thus the cutting like a truecutter or chisel. The teeth are ultimately set in the usual manner. The material cut bv each tooth is largely in the form of strips or shavings which roll 'or curl up, and the total bulk of edge 62 acts has I pivoted therewhich resulting from one passage of the the return stroke is toward this shaft.

Sinee-the' return stroke is in idlestroke, it

is desirable that it. shall be performed as uickly as possible. It isalso desirable that Y t e working or-cutting' stroke shall be performed at as nearlya uniform rate of speed as possibe. The reciprocatory movement essentially requires, however, that the saw shall cometo a dead stop at both ends of its movement. A crank or eccentric connection,

which is usually anddesi-rably employed for reciprocating the. saw frame, also Involves irregularity in the rate of movement.

- tion roller 66 on this crank pin Titles in the slot 67 of'a radially slotted crank arm The construction illustrated i within practical limits, while making use of the crank means for effecting the reeipro;

catory movement of the saw frame,. to'

approximate uniformity of rate of move,-

ment of the saw blade during the cut-- ting stroke. In the construction illustrated,

the saw frame 24' is connected by a.link

63 pivoted thereto at 64 with a crank pin 65 on the crank disk 23. .An anti-fric- 68 mounted on and splined at 69 to the cam shaft 18. Since the axis 22 of the crank disk 23 is-well above the axis-18 of the crank arm 68, thecutting-stroke of the saw frame will take lace with relatively; slow move ment during a relatively large angle of rotation ofthe cam shaft 18. whilethe return stroke will take place with a relatively quick movement'through a comparatively small angle of rotation of thecam shaft. 1

' A mechanism by which the saw frame and saw blade are continuously, positively and uniformly fed relatively to the work support during the cutting stroke is, as already pointed out, preferably of a type involving a positively acting feed screw. A simple and preferred form of such feeding mechanism is illustrated. V

A feed screw frame comprisingxthe standard 70, the base 71, and the overhanging top 72' is mounted at aconvenient position on the supporting bed. For this purpose the standard is shown as provided with an integral vertical sleeve73 fitting over the post. 74 rigidly secured bythe nut 75 in the supporting bed" 1. A feed screw 76 is verticallymounted in the screw frame. This feed screw is swivelled in the overhanging top 72 so as freely to be rotatable inthe frame. At its lower end it is journalled in the base 71 and passes down therethrough and has an "end hearing at 77 in a bearing sleeve 78 in the supporting bed 1. A nut 79 cooperatingwi-th the feed screw '76 is held against rotation by means of a vertical rib 80 mounted to slide in a vertical .slot in the standard 70 of the feed screw frame. This rib has pivoted thereto at 81' a link 82,

the upper end of which is'pivoted at 83 to the saw frame guide arm 27. It will thus that as the feed screw 76 is rotated nism operated-from the cam shaft 18. A

'rotatab e element in the form of a ratchet heel 85 is-mounted on .the supporting bed, direct] spline -at 86 to the fee screw 76 so as to rotate therewith.. The bearing sleeve 78,

which is itself journalled in the supporting.

bedl, has integrally formed therewith a radially projecting arm 87 forming a pawl" over? the bearin sleeve 78, and is.

carrier for'apawl 88 pivoted thereon at '89 and cooperating with the ratchet wheel 85. A spring 90' seated in the pawl carrierand abuttinga'pin 91 on the pawl 88 serves to hold it yieldinglX in engagement with the ratchet wheel. detent pawl 92 may be provided to prevent reverse rotation ,of the ratchet wheel. The pawl carrier 87 is connected by a link 93 pivoted thereto at 89 to a rocker arm 94 ivoted at 95 on the sup porting bed 1. his link.93' is adjustable radially of the rocker arm 94 by means of a set screw 96 adjustably mounted in the arcsha ed slot 97 ofthe rocker arm. A link 98 asa' pivotal connection at 99 with the rocker arm 94, and at its other end at 100 is pivotally-eonnected to a clevis 101 which is pivotally mounted at 102 in the end of one arm 103 of a bell crank lever fulcrumed at 104 on a standard 105 projecting upwardly from the supporting bed. The other arm 106 of the bell crank lever carries at its-free end a roll 107 riding in the cam groove 108 of a face cam 109 splinedto the cam shaft 18, ,The cam groove 1080f the cam 109 is so designed as to transmit through the train of mechanism described to the ratchet wheel 85, and consequently to the fee'd'screw at each rotationof the camshaft, a feeding movement, during that period of rotation of the cam 109which takes place simultane ously with the cutting stroke of the saw blade, which is substantiallyuniform per unit of the cutting stroke. The angle of rotation of the shaft 18 which effects the cutting stroke of the saw blade corresponds to the obtuse angle between'the radial lines 110 and 111, see Fig. 10. The cam groove 108 throughout this obtuse angle of rotation is therefore designed to give a feeding movleto t e ment. which. shall becom ensato more or less variable cutting stro e reciprgcation of the. saw frame so thatas a resulteach increment of feeding movement of the saw blade. toward the work support bears iao a substantially uniform ratio to'each in; crement of movement of the cutting stroke, that is to say, the feeding movement varies in correlation with the speed of the saw and in substantially the same proportion as the variations in the s eed of the saw so that each cutting tooth 1s fed into the work-at a rate which is proportional to the speed of the saw. The feeding movement, it w1ll be observed, takes place in only one direction, and the return movement of the feedlng mechanism takes place during the return stroke of the saw blade and while the cam 109 is moving through the acute angle between the lines 111'and 110.

The rate of feeding movement is adjusted or varied with respect to the cutting stroke so as to vary the rate of feed relatively to the speed of the saw blade in its. cutting stroke by adjusting the end of the lmk 93 in the slot 97 of the rocker arm 94.

The saw blade must not be allowed to drag over the work during the return stroke, else the teeth will become dull. Consequently it is necessary to lift the saw blade at the beginning of the return stroke so that the return stroke will take place in a path above the cutting stroke and then to lower the saw blade into position for the succeeding cutting stroke. In the construction illustrated, this is done by raising and lowering the feed screw frame which, by means of the link 82, the nut 79, and the feed screw is rigidly connected to the saw frame guide arm during the return stroke. The sleeve 73, it will be remembered, guides the feed screw frame vertically on the stud 74 and a smaller stud 112 mounted in the supporting bed and passing through an aperture 113 in an extended portion of the base 71 of the feed screw frame acts as a further vertical guide therefor. The sleeve 73 is connected by a link 114 to a slide bar 115. This slide bar at one end slides between recessed blocks 116 and 117 rigidly mounted on the top of the post 74 and held in place by the nut 118. At its opposite end the slide bar 115 is pivoted at 119 to a rocker arm 120 which is pivoted at its lower end at 121 to the supporting bed 1 and at its upper end carries a roll 122 riding in the cam groove 123 of the cam 124 secured to the cam shaft 18. When the cam 124 moves the slide bar 115 to the right or into the position shown m Fig. 7, the vertical distance between the plv' otal ends of the link 114 is shortened and as the slide bar is rigidly supported vertically, the sleeve 73, and with it the saw frame guide arm, is lifted. The cam groove 123 15 so designed as to cause the cam to be in this position during the return stroke of the saw blade. When the cam moves the slide bar 115 to the left, the sleeve 73, and with it the saw frame guide arm, is lowered into the position required during the cutting operation or at any required stroke. The rotatable element or ratchet wheel is restrained from participat ng in this lifting and lowering movement by the late 125, which is secured to the supporting ed and overhangs the ratchet wheel. This plate may also serve as. a friction plate, in cooperation with or as a substitute for the detent pawl 92, to prevent undesired rotation of the ratchet wheel. For this purpose the plate 125 is shown as seated on two studs The plate 127 serves as a spacer between the ratchet wheel and the supporting'bed, and also as a further support for the studs 126.

The inner stud 126 carries-a pair of lock.

- 126 arranged radiallyof the ratchet wheel.

and the saw frame may be effected readily and quickly with the saw frame at anypoint of elevation with respect'to the work suport. Simple and efficient means for securmg these results are provided in the construction illustrated. The nut 79, hereinbefore referred to as cooperating with the feed screw 76, is preferably in the form of a split but being made, in the form illustrated, in

two parts, which when moved together en-' gage the screw, and when moved apart allow the nut to pass freely over the screw. These parts 129 and 130 are mounted to slide horizontally toward and from each other on the pins 131 mounted in'the vertical rib 80. A helical spring 132 seated in opposing recesses in the nut parts between the pins 131 acts normally to separate the nut parts. A latch 133 is pivoted at 134 to the nut part 130 and is provided with a bayonet slot 135 engaging a stud 136 on the other nut part 129.

striker pin 137 is vertically and adjustably mounted in the base 71 of the feed screw frame beneath the latch 133. It will thus be seen that by raising the latch 133 manually, the nut is freed from the feed screw so that the saw frame guide arm may be raised and lowered independently of the feeding mechanism, as when required in startin the sawing operation. Furthermore, by setting the striker pin 137 at the right height, the latch 133 will be released so as to release the nut from the feed screw and thus stop the feeding movement of the saw frame at the conclusion of the sawing oint therein.

It will thus be seen that w on the split nut is engaged withthe feed screw and the machine is in operation, the saw frame guide arm will be fed toward the work support during each cutting stroke continuously and positively at a rate dependent upon the ad- I 20. having g limitation.

the

f th

I justment of the link 93 in the slot 97 of the rocker arm '94. It will also be seen that thissfeeding movement, whatever may be the adjustment as to the rate of feed, is uniform because there can be no feedin of the guide arm, saw frame an saw except as given by the screw. The saw blade is not only positively and continuously fed toward the work, but it is also positively and 40 continuall restrained from having any additional eedingmovement. consequent] there can when the teeth engage a spot of lam resistive properties than that of the main rtion of k. This is the preferre form of the invention, but many advantages of the invention'may be secured, so long as the feeding movement is positive and continuous andso long as the saw is prevented from a greater than the predetermined de of penetration throughout the cutting fie d.- While in the latter case the feedin movement might not be uniform, there woul be a uniformity of limit of movement dura each cutting stroke. It is, of course, to be understood that the saw blade must accurately guided both in its reciprocatory movements and in its movements toward and from the work support, but as this involves details of i mechanical construction not involved'in the present invention, it may be -leftto ordinary mechanical skill.

Terms such as vertical upper lower, etc., which have been used herein areto be '5 taken as terms of relation merely'and notof Suitable means will usually be provided for delivering a liquid lubricantj upon the saw blade as 1t a as such means are well known-and common andform no part of the present invention,

are not herein illustrated. 1 machine constructed in acc ordance with principles of this invention operates in as. practice to at high speed and with a true cuttin action, .as disti ished from a filing or a rading v -action.- wing to this true cutting action, 7 the life of the saw blade is prolonged into definitely. Furthermore, withthe positive, a

continuous and uniform feed the time required to make a cut in agiven piece of stock can predetermined with great accuracy and each successive cutwillbe made in the same I time.

They reciprocating type of saw embodying this invention can be constructed at relatively less expense than a band saw machine embodying the invention and the reciprocat- I ing type of machine also employs short, and

therefore far less expensive, saw blades. But for a large range of work the reciproeating type'of saw is thoroughly practical and, eilcept in cases requiringspeedof opermovement be no digging in of the saw bla e.

passes through the stock, but;

cut metal with great efliciency;

ation, will give most of the advantagesof u the larger machme; o v

Itfs also to be remembered that a machine of this type, using the thin saw blade, wastes'a mimmum amount of material in making thecut, which is very important in the case of expensive materials.v 17 The operator, with a little experience will find no difliculty in bringing the spec of the saw.- ,blade, the feeding movement thereof, the resistive properties of the stock being'cut, thegmaximum width of the cutting field of the being cut and the gullet capacity of thefsaw into correlation in accordance with the principles of this invention. For standar qualities of material a table may be prepared showing at what point, with a saw blade of given gulletcapacity and for different widths of cut, the link 93 should be set and to what speed the pulley 5 should be adjusted in order to effect the desired correlation.

Having thus described the invention, what is claimed as new, and desired to be secured by Letters Patent, is:

1. A metal cutting machine comprisin a work support, a saw blade having an e ge provide with teeth and with gullets inter-- mediate the successive teeth of sufiicient capacity to permit the coiling therein of. strips of metal cut from the stock by the respective teeth throughout the cutting field, means for reciprocating the saw blade to give the cutting stroke and a return stroke in a path above the path of the cutting stroke, and means acting during the cutting stroke continuously and positively to feed the saw blade relatively to the work support and to prevent greater than a predetermlned depth of penetration, in which machine the speed of the saw during the cutting stroke, the feeding movement thereof, the resistive properties of the stock being cut,'the maximum cutting field of the stock being cut and the capacity of the gullets of the saw are correlated to cause each tooth during its cutting engagement with the stock to cut metal therefrom of a maximum bulk not greater than the capacity of a gullet.

2. A metal cutting machine comprising a work su' port, a saw blade having an edge provided with teeth and with gullets intermediate the successive teeth of sufiicient capacity to permit the coiling therein of stri of metal cut from the stock by the respective teeth throughout the cutting field, means for reciprocating the saw blade to ive the cutting stroke and a return stroke' m a path above the path of the cutting stroke, means acting during the cutting stroke continuously, positively, and uni- --forml r unit of cuttmg stroke to feed the saw b a e relatively to the work support, in which machine the speed of the saw during provide mediate being cut, the maximum cutting field of the stock being cut and the capacity of the gullets of, the saw are correlated to cause each tooth during its cutting engagement with the stock to cut metal therefrom of a maximum bulk not greater than the capacity of a gullet.

3. A metal cutting machine comprising a work su port, a saw blade having an edge d with teeth and with gul ets interthe successive teeth of sufiicient capacity to permit the coiling therein of strips of respectiveteeth throughout the cutting field, means for giving a variablereciprocatory movement to the saw blade to give a cutting stroke and a returnstroke in a path above the path of the cutting stroke, and means acting during the cutting stroke with a variable movement compensatory to the reciprocatory movement to feed the saw relatively to the work support continuously, positively, and uniformly per unit ofcuttin'g stroke, in

which machine the speed of the saw during the cutting stroke, the feeding movement thereof, the resistive properties of the stock being cut, the maximum cutting field of the stock being cut and the capacity of the gullets of the saw are correlated to cause each tooth during its cutting engagement with the stock to cut metal therefrom of a maximum bulk notgreater thanthe capacity of a gullet.

4. A metal cutting machine comprising a horizontal work support, a vertically and longitudinally movable saw frame, a saw blade mounted in the frame having an edge provided with teeth and with gullets intermediate the successive teeth of snfiicient cae pacity to permit the coiling therein of strips of metal cut from the stock by the respective teeth throughout the cutting field, means for longitudinally reciprocating the saw frame to give a cutting stroke and a return stroke in a; path above the path of the cutting stroke, feeding means acting during the cutting stroke continuously, positively, and uniformly per unit of cutting stroke to feed the saw frame toward the work support, means for connecting the feeding means to the saw frame when the frame is in any vertical position, and -means acting auto- -matically to disconnect the feeding means and saw frame when the saw blade has been fed to a predetermined position with respect to the work support, in which machine the speed of the saw during the cutting stroke, the feeding movement thereof, the resistive properties of the stock being cut, the maximum cutting field of the stock being cut and the capacity of the gullets of the saw are correlated to cause each tooth during its longitudinally movable on the metal cut from the stock by the cutting engagement withjthe stock to cut metal therefrom of a maximum bulk not greater than the capacity of a gullet.

5. A metal cutting machine comprising a supporting bed, a work support on the bed, 7

a verticallymovable guide arm, a saw frame ide arm, a.

saw blade mounted in the'saw rame, means for longitudinally reciprocating the saw frame on the guide arm to give alternating cutting and return strokes having initial accelerated and final retarded movements, means for lifting the guide arm at the beghsning and'for lowering it at'the end of the returnstroke of the saw blade, and

feedingmeans connected to' the-guide arm acting during the cutting'stroke to feed the guide arm continuously and positivelyrelatively to the 'worksupport and alsoacting A to vary thefeeding movement in correlation with and in substantially the same proportlon'as the variations in' the speed of the saw.

6. A metal cutting machine comprisin a supporting bed, a work support on the be a vertically movable guide arm, a saw frame longitudinally movable on the guide arm, asaw blade mounted in the saw frame,

means for longitudinally reciprocating the saw frame on the guide arm to give alternating cutting and return strokes having initialaccelerated and final retarded movements, means for lifting the guide arm at the beginning and for lowering it at the end of the return stroke of the saw blade, feeding means connected to the guide armacting duringthe cutting stroke to feed theguide arm continuouslyvand positively relatively' to. the work support and also acting to vary the feeding movement in correlation with and in substantially the same proport 1on as the variations in thespeed of the saw, and means for adjusting the feeding means to adjust the rate of movement of the guide arm.

7 A metal cutting machine comprising a supporting bed, a work support on the bed, a vertically movable horizontally extending guide arm, a saw frame longitudinally movable on the guide arm, a saw blade mounted in the saw frame, means for longitudinallyreciprocating the saw frame on the guide arm to give alternating cutting and returnstrokes having nitial accelerated and final retarded movements to the saw blade, means for lifting the guide arm at the beginning and for loweringit at the end 'of the return stroke of the saw blade a fixed distance to prevent the saw. blade dragging on the work during the return stroke, feeding means connected to the guidearm and acting during the cutting stroke to move the guide arm continuously, and positively toward the work support and to va the feeding new in obi-remiss 'wit and in substantially the-same propor-' tion as" the variations in the speed of the vary 'therate of movement o the guide B A metal cutting machine comprising a su portin' .bed, a saw frame vertically and" o 'tu inally' movable with respect to Y the bedt ii saw blade mounted in the frame,

means for longitudinally reciprocating the saw frame to give alternating cutting and return strokes to the saw blade, afeed screw,

means for positively rotating said feed screw continuously during the cuttm -stroke, a nut cooperating with the f screw and releasable therefrom, a connection between the nutand the. saw frame whereby the rotation of the feed screw will feed said saw frame relatively to the suprting bed, and means for automatically predetermined operation.

9.rA metal cutting machine comprising a supporting bed, a saw'frame vertically and point during the feeding longitudinally movable with respectrtothebed, a 'saw blade mounted in the saw frame, means' for longitudinally reciprocating the saw frame to "give alternating cutting and j return strokes to the saw blade, a feed screw frame mounted and vertically movable toward and fromthe bed, a feed screw rotat-j ably mounted in the feed screw frame, means r for rotating the feed screw during the cut- .the latter moves with the former, and means for lifting the screw frame at the beginting stroke, a nut coo rating wit the feed screwjand releasabl t erefrom, a connection between the nut a the saw frame whereby ning, and for lowering-it at the end. of the return stroke of the saw frame and means for automatically disengaging said nut from said screw at a predetermined point during the feeding operation;

'10. A metal cutting machinecomprising a'supportin bed, a saw frame vertically and longitu inally movable with t to the bed, a saw blademounted i t e saw frame, means for longitudinally reciprocat ing the saw frame to give alternating -cut ting and return strokes to the saw blade, a:

feed. screw frame mounted and vertically movable on the bed, a rotatable. element mounted, and vertically immovableon the bed, .a'feed screw rotatably mounted on the screw frame and splined to the rotatable element to rotate therewith, means for rotating the rotatable-element to effect a con-- tinuous-, and positive feeding-movement-to ward the work support and to va --the feeding movement- 1n correlation wit and in substantially the same proportion as the lsengagingthe nut from said screw at a' saw frame-to give alternating variations in the sp'e'ed'of the has 'nut cooperating'with the feed screw, a connec t tion' between the nut and the sawgframe to. "'15 '1 cause the latter to move withlthe former-,3?

and mean'sfor lifting the screwiframe at -the, beginning and 'for lowering it of the return stroke.

11. A metal. cuttin h' emb i s the construction de ned infclaim 10j-in to vbring the saw blade "tea. predetermined -point from the supporting bed, I

12. A metal cuttin machine omprising the construction de ned in "'claim1"f10 in 'I which the said nut is split, to. ther with means acting normally to open'i t e -nut and release it from the feed screw, ailatchto retair thesplit nut closed, and aflstriker pin in position to engage'and release the latch A when the feed screw. has fed the; nut to bring the saw blade to a" .redetermined point from the sup rting be 1 '13. A metal cutting machineycomprising' the construction defined in 'claim -10 in a whichthe said means for, lifting and lower- 1 ing the screw frame comprises a rotatable cam, a slide bar held against vertical movement, means operable by said cam to reciprocate the slide barhorizontally upon each rotation of the cam, and a connection between the slide bar and'screw frame act- 7 .ing when the slide bar is moved in one direction to lift, and when moved in the other direction to lower, the screw frame. 106- 14. A metal cutting machine comprisin a supporting bed, a saw frame vertically-an longitudinally movable with respect to the bed, a saw blade mounted in' the frame, means for longitudinally reciprocating the 110 saw frame to give alternating cutting'fand 1 return strokes to the saw blade, afeed screw,

means for positively rotating said feed screw continuously during the cutting stroke, means for positively maintaining the feed screw against vertical movement during the cutting stroke, a nut cooperating with the feed, screw, a connection between the nut and the saw frame whereby the ro-' tation of the feed screw will feed said saw frame relatively to the supporting bed.

15. ,A metal cutting machine comprisin a supportinfi bed, asaw frame vertically an longitudina movable with respect to the bed, a saw lade mounted in the frame,

means for longitudinally reciprocating the,

cutting and return strokes to the saw blade, a feed screw, means for positively rotating said feed screw continuously the cutting my stroke, means for positively maintaining the feed screw against vertical movement during the cutting stroke, a nut cooperating with the feed screw, a connection between the nut andthe saw frame whereby the retation of the feed screw will feed said saw frame relatively to the supporting bed, and means for positively lifting the e at the beginning and for sitively lowering it at the end of the cutting stroke.

,16.' A metal cutting machine comprising a supporting bed, a saw frame vertically and longitudinally movable with respect to the bed, a saw blade mounted in the saw frame, means for longitudinally reciprocating the saw frame to give alternating cuttingand return strokes to the saw blade, means acting positively and continuously to feed the saw during the cutting stroke including a feed screw, a ratchet on said feed screw, a pawl engaging said ratchet, a movable pawl carrying arm, a rocker arm, and means for oscillatm the rocker arm and means connectin t e rocker arm to the pawl carrying 2 arm a justable longitudinally of, therocker ed screwarm to vary the am litude'of movement of the pawl carrying t e arm.

17. A metal cutting machine com rising a supportingbed, a saw frame vertica ly and longltudinally movable with respect to the bed, a saw blade mounted in the saw frame, means for longitudinally reciprocating the saw frame to give alternating cutting and return strokes to the saw blade, means acting positively and continuously to feed the saw during the cutting stroke including a feed screw,a ratchet on said feed screw, a pawl engaging said ratchet, a movable pawl carrying arm. a rocker arm having a longitudinal slot therein, means for oscillatin the rocker arm, a link connected at one en to the pawl carrying arm and having means adjustable in the slot of the rocker arm to connect the link thereto, whereby the amplitude of movement of the pawl carrying arm maiy be varied.

n testimony whereof, we have slgned our names to this sfiecification.

' A THUR G. THOMPSON.

LINUS K. SPRAGUE. 

